I went to kill the ender dragon my first time in a single player survival world. I destroyed all the crystals and got the dragon to 0 health, but she didn't die. She just keeps doing her whole routine of flying around, shooting, and settling on the pedestal, but I am unable to harm her. I tried leaving and re entering the world, but all that did was bring her back to full health. The crystal's are still destroyed and I am still unable to hit her, leaving me stuck in the end dimension as I am not willing to die and lose all of my stuff.